Your journey to motherhood with the comfort of knowing that everything will turn out well
Want to be a mother, but worried that your baby may be born with a genetic disorder? Preimplantation genetic diagnosis can help you fulfil your dream with all the guarantees that go hand-in-hand with a clinic like ours, with its own lab and state-of-the art assisted reproductive technology.
What it is
Preimplantation genetic diagnosis (PGD) is a scientific method which allows to study the genetic characteristics of an embryo before it is transferred to the uterus, in order to prevent your future child from being born with a hereditary disorder.
This technique is useful in couples with high genetic risk and to improve the efficiency of an In Vitro Fertilization process.
The first PGD pregnancy in Spain was achieved in 1994 in our hospital in collaboration with the Universitat Autònoma de Barcelona (UAB) to prevent the conception of a child with haemophilia in a couple where the mother was a carrier of the disease. Since then many couples have benefited from this technique.
In July 2006, our Obstetrics Department together with the Biomedical Division of the company Sistemas Genómicos achieved the first Multiple Hereditary Exostosis-free pregnancy in the world, using the Preimplantation Genetic Diagnosis technique.
Step by step
Regardless of the genetic disorder that may affect you or your partner, at Dexeus Mujer, the process involves the following steps:
To conduct this procedure, it is necessary to obtain embryos from the couple using IVF techniques even when there are no infertility issues.
The biopsy does not jeopardise the development of the embryo.
The cryopreservation is carried out by vitrification.
Depending on the pathology we are analysing, we will use different techniques (NGS or PCR).
The transfer of a single embryo is recommended, since the chances of pregnancy using this technique are higher than after a conventional in vitro fertilisation.
1. In vitro fertilisation
To conduct this procedure, it is necessary to obtain embryos from the couple using In Vitro Fertilisation (IVF) techniques even when there are no infertility issues.
2. Embryo biopsy
Embryo biopsy is the process by which the embryonic cells to be analysed are obtained. This procedure does not compromise the subsequent viability of the embryo provided it is carried out by expert embryologists. Dexeus Mujer has certified senior embryologists with extensive skills and experience in micromanipulation.
Several scientific publications have shown that blastocyst stage embryo biopsy offers better results than in early embryos. Our group always performs the biopsy at this stage of embryonic development.
In order to perform the embryo biopsy, it will be necessary to dissect the zona pellucida of the embryo (embryonic coat) on the third day of development. This opening is made by using a laser connected to the microscope.
Between the fifth and seventh day after insemination, some embryos are able to form a blastocyst. Embryos that reach the blastocyst stage are biopsied. During the process, between three and eight embryonic cells are extracted and subsequently tested.
Once the embryo biopsy is completed, the blastocyst is cryopreserved immediately, using the vitrification technique, and it remains frozen until it is used.
Our centre described for the first time in the world a pregnancy after the transfer of a biopsied embryo obtained within the Preimplantation Genetic Diagnosis program, that had been cryopreserved using the vitrification technique.
Embryo biopsy performed at the blastocyst stage.
3. Biopsied embryos cryopreservation
Excess viable blastocysts that have been diagnosed as normal are cryopreserved for future transfers by the vitrification technique.
4. Diagnostic genetic analysis
The biopsy obtained is then processed for analysis by means of NGS (Next Generation Sequencing) or Polymerase Chain Reaction (PCR) depending on the disease being analysed.
In cases where it is required to analyse the chromosomes of the embryos, either because of an increased risk of aneuploidies or due to chromosomal rearrangements, the NGS technique is used. This technique is the one that, today, offers a greater diagnostic sensitivity.
Result of the chromosomal analysis of a euploid embryo tested by NGS.
The PCR technique is used for the diagnosis of monogenic diseases. With this process, the presence of the altered gene is detected using specific DNA sequence amplification.
The diagnostic efficiency with the PGD technique is about 95%.
5. Embryo transfer
With the result of the genetic analysis, the cryotransfer of the embryos diagnosed as euploid or non-affected can be programmed. The transfer of a single embryo is recommended, since the chances of pregnancy using this technique are higher than after a conventional In Vitro Fertilization. If surplus transferable pre-embryos exist, they will remain cryopreserved for later cycles.
Who it is for
Preimplantation Genetic Diagnosis is advisable if either you or your partner:
- Have a risk of transmitting a genetic disorder to your offspring.
- Have chromosomal abnormalities.
- Have had repeated miscarriages or repeated implantation failures.
- Have completed IVF cycles without success.
- Have a genetic predisposition for cancer.
- Have a child with a serious disorder requiring a transplant, and need to achieve pregnancy and to deliver a compatible donor.
Couples with a high genetic risk
Monogenic diseases are those caused by a specific gene mutation (cystic fibrosis, thalassemias, fragile X syndrome, etc.). To prevent the transmission of this disease by use of PGD it is essential to know the mutation causing the disease.
The number of the identified monogenic diseases is above 6,000, and many of which could cause severe health disorders. See the list of monogenic diseases analysed with PGD.
If, after a preconceptional genetic test, an increased risk has been detected for the offspring, it is possible to analyse the embryos to avoid future children being affected by the disease in question.
In cases of PGD of monogenic diseases, it is necessary to carry out a study of informativity prior to the PGD cycle to confirm that the diagnosis is feasible and adjust the technique to each case.
Chromosome abnormalities, numerical or structural
The presence of a chromosome reorganisation (Robertsonian translocations, reciprocal translocations and inversions) in one member of the couple may lead to difficulties in conceiving, miscarriages or congenital malformations. The use of PGD in these couples is extremely useful.
Both in the case of monogenic diseases and those associated with chromosomal reorganisation, it is necessary to conduct a genetic informativity study before the PGD cycle to confirm that the diagnosis is reliable and to adjust the technique to each individual case.
It is also indicated in cases of numerical chromosome abnormalities, pure or mosaic.
Couple coming from IVF programmes
The main cause of absence of pregnancy after a cycle of In Vitro Fertilization is the presence of chromosomal abnormalities in the transferred embryos. In the same way, the majority of first trimester miscarriages are caused by the implantation of an embryo with some chromosomal anomaly.
The Preimplantation Genetic Diagnosis allows to complement an In Vitro Fertilization process, identifying embryos with alterations in the number of chromosomes and discarding them for the transfer. Only euploid embryos or with a normal chromosomal envelope are transferred. With this selection, it is possible to reduce the time to get a pregnancy and it reduces the chances of miscarriage and of conception affected by chromosomopathies.
There are certain factors that can predispose to an increased production of embryos with alterations in the number of chromosomes. In these cases, performing a PGD is especially beneficial:
- Advance maternal age (>37 years).
- Altered male meiosis.
- Couples with repeated miscarriage.
- Couples with repeated implantation failures.
Predisposition to certain diseases
It is known that mutations of some gene predispose individuals to certain diseases that may appear at different life stages, such as neurofibromatosis, familial adenomatous polyposis or genetic breast cancer (BRCA1, BRCA2), etc.
When a hereditary disease component is confirmed, the possibility of PGD would allow the possible appearance of this disease in the next generation to be avoided.
In some of these cases, the express authorisation from the Health Authority is necessary in order to conduct PGD, following a favourable report of the National Commission of Human Assisted Reproduction which assesses the particular social, therapeutic and clinical characteristics.
The current law governing assisted reproduction techniques (Law 14/2006) considers the possibility of conducting a PGD cycle to determine the histocompatibility antigens for therapeutic purposes for third parties. This is used when a first-degree relative, generally a child, suffers from a serious hematopoietic disease that requires the transplant of histocompatible bone marrow or umbilical cord cells.
In order to conduct PGD-HLA, express authorisation from the corresponding Health Authority with a prior favourable ruling from National Commission of Human Assisted Reproduction which evaluates the social, therapeutic and clinical characteristics of each case.
The first child born after the application of PGD-HLA was in the USA in 2000. This permitted the successful donation of umbilical cord cells to his sister who had Fanconi anaemia.
List of monogenic diseases
The number of the identified monogenic diseases is above 6,000, and many of which could cause severe health disorders.
List of monogenic diseases analysed with PGD:
- Alpha thalassaemia
- Alpha-1-antitrypsin deficiency
- Alport syndrome
- Amyotrophic lateral sclerosis
- Beta thalassemia
- Congenital disorder of glycosylation type 1a
- Crouzon syndrome
- Cystic fibrosis
- Duchenne and Becker muscular dystrophy
- Dystonia 1, Torsion
- Emery-Dreifuss muscular dystrophy
- Facioscapulohumeral dystrophy
- Familial adenomatous polyposis
- Familial amyloidotic polyneuropathy
- Familial dysautonomia
- Fanconi anaemia
- Fragile X
- Glutaric aciduria type 1
- Haemophilia A and B
- Hemophagocytic lymphohistiocytosis
- Holt-Oram syndrome
- Huntington's disease
- Hyperinsulinemic hypoglycemia
- Hypokalaemic periodic paralysis
- Incontinentia pigmenti
- Lynch syndrome
- Marfan syndrome
- Menkes disease
- Metachromatic leukodystrophy
- Mucopolysaccharidosis type II (Hunter syndrome)
- Multiple endocrine neoplasia (MEN2)
- Multiple exostosis
- Myotonic dystrophy
- Neurofibromatosis type I and II
- Non-syndromic Sensorineural Deafness
- Norrie syndrome
- Osteogenesis imperfecta (brittle bone disease)
- Polycystic kidney, autosomal dominant
- Polycystic kidney, autosomal recessive
- Pompe's syndrome
- Sickle cell anaemia
- Smith-Lemli-Opitz syndrome
- Spastic paraplegia 4
- Spinal and bulbar muscular atrophy
- Spinal muscular atrophy
- Spinocerebellar ataxia 1, 2 and 3
- Spondylometaphyseal dysplasia (Schmidt)
- Tay-Sachs disease
- Treacher Collins
- Tuberous sclerosis
- Von Hippel-Lindau syndrome
Performing a PGD cycle for these diseases does not require the express authorization of the health authorities.
Why choose us
We are pioneers in reproductive medicine. We have more than 80 years’ experience behind us and a team of highly qualified and specialised professionals. The first Spanish test-tube baby was born in our clinic (1984) and Spain's first egg donation treatment was carried out here, which culminated in the birth of twins (1988). In 1994, in partnership with the Autonomous University of Barcelona, we achieved the first successful post-PGD pregnancy in Spain, which culminated in the birth of two healthy baby girls from a mother with haemophilia.
We have our own PGD laboratory, which is equipped with state-of-the-art technology, and a highly qualified team of experts in this high-precision method.
Extensive experience, quality and cutting-edge technology. We have one of the top in vitro fertilization laboratories in Europe where we perform over 3,000 cycles (assisted reproduction techniques) each year. We offer the latest advances in assisted reproduction, such as intracytoplasmic sperm injection (ICSI) and real-time monitoring of embryo development (dynamic monitoring).
High success rate. 25% of our patients have a history of treatment failure in other clinics. However, our success rate is around 45-55% at the first attempt, with an overall cumulative rate of around 80%.
Personalised service. We will guide you through the entire process, offering personalised treatments suited to your needs. You can also contact our medical team directly at any time.
Silvia, 37 years old. Barcelona
"I am a carrier of a hereditary disease, just like my brother and my father are. At the time that my husband and I considered having children, I knew that I did not want them to suffer from the family illness and have the same problems that we have. For this reason, we went to Dexeus Mujer and there they explained us that we could select healthy embryos. After undergoing an IVF treatment, we got 5 embryos, two of them healthy. Our first daughter has just been born and we couldn’t be happier!"